🫁 Chapter 24: Acute Care of Chronic Lung Disease

Bronchopulmonary dysplasia (BPD) · Cystic fibrosis · Acute-on-chronic respiratory failure · ABG clues (↑HCO3, ↑PaCO2) · Ventilatory strategy (low rate, long expiratory time, permissive hypercapnia) · NPPV · Pulmonary hypertension · Weaning · Discharge planning

🔍 Core Concepts: Acute Care of Chronic Lung Disease

📌 Aetiologies
Infants: BPD (bronchopulmonary dysplasia). Older: cystic fibrosis, interstitial lung disease, bronchiectasis. Acute exacerbation often triggered by infection.
🩸 ABG clues (acute-on-chronic)
pH low/normal, PaCO2 ↑, HCO3 ↑ (renal compensation). Normalisation of blood gases is NOT the goal; accept baseline PaCO2.
💨 Ventilatory strategy
Low rate (age-appropriate low), long expiratory time (I:E 1:3 or 1:4), PEEP 0-5 (if auto-PEEP present, set PEEP ~2/3 of measured auto-PEEP). Target SpO2 >90%.
⚕️ NPPV role
Non-invasive positive pressure ventilation (BiPAP/CPAP) decreases need for invasive ventilation and shortens duration. Use post-extubation for residual distress.
💊 Adjunctive therapies
Broad-spectrum antibiotics (cover Pseudomonas, H. influenzae, S. pneumoniae), chest physiotherapy, bronchodilators, steroids (if reactive airway disease).
📉 Weaning & extubation
Goal is not normal PaCO2. Wean when haemodynamically stable, PaO2 >60, PaCO2 at baseline. Sprint weaning technique. Avoid excess carbohydrates (increase CO2 production).

🩺 Stepwise Approach: Acute Exacerbation of Chronic Lung Disease

1
Recognize acute-on-chronic pattern
Clues: known CLD (BPD, CF), tachypnoea, increased work of breathing, baseline CO2 retention. ABG: pH ↓ or normal, PaCO2 ↑, HCO3 ↑. Look for infection trigger.
2
Supplemental oxygen & monitoring
Give O2 to maintain SpO2 >90%. Avoid excessive O2 (may worsen hypercapnia via Haldane effect). Target SpO2 88-92% if hypercapnic risk. Consider echocardiography for pulmonary hypertension.
3
Non-invasive ventilation (NPPV) first line
Trial of BiPAP/CPAP if moderate distress, intact airway reflexes, haemodynamically stable. Settings: IPAP 10-15, EPAP 5-8, backup rate. Monitor for improvement.
4
Invasive ventilation (if NPPV fails or severe)
Indications: altered mental status, haemodynamic compromise, profound hypoxaemia, pH <7.25 despite NPPV. Ventilator strategy: low rate (age-appropriate low), long expiratory time (I:E 1:3-1:4), PEEP 0-5 (if auto-PEEP, set external PEEP ~2/3 measured).
5
Adjunctive medical therapy
Broad-spectrum antibiotics (cover Pseudomonas, Strep, H. influenzae), bronchodilators (nebulized salbutamol/ipratropium), steroids if reactive airway component, chest physiotherapy, treat pulmonary hypertension if present (sildenafil, iNO).
6
Weaning & extubation
Goal: return to baseline PaCO2, not normal. Use sprint weaning technique. Consider early extubation to NPPV to prevent VAP. Accept higher PaCO2 if pH >7.30. Optimise nutrition (avoid overfeeding carbohydrates).